upgraded requirements for django 2.2

requirements.txt

 boto==2.49.0
 DateTime==4.3
-Django>2.1, <2.2
+Django>2.2, <2.3
 django-autoslug==1.9.6
 django-braces==1.14.0
 django-cas-client==1.5.3
 django-crispy-forms==1.8.1
 django-gravatar2==1.4.4
 django-haystack==2.8.1
-django-model-utils==3.2.0
+django-model-utils==4.0.0
 django-piwik==0.1
 django-randomslugfield==0.3.0
 django-ratelimit==2.0.0
-django-redis-cache==1.8.1
+django-redis-cache==2.1.0
 django-smtp-ssl==1.0
-django-storages==1.7
-djangorestframework==3.9.4
-docutils==0.15.2
-flake8==3.6.0
-gunicorn==19.10.0
+django-storages==1.9.1
+djangorestframework==3.11.0
+docutils==0.16
+entrypoints==0.3
+flake8==3.7.9
+gunicorn==20.0.4
 mccabe==0.6.1
-mysqlclient==1.3.14
+mysqlclient==1.4.6
 pep8==1.7.1
-Pillow==5.3.0
+Pillow==6.2.2
 pycodestyle==2.4.0
 pyflakes==1.0.0
 pyisbn==1.0.1
@@ -31,5 +32,6 @@ redis==2.10.5
 requests==2.11.1
 selenium==2.45.0
 six==1.10.0
+sqlparse==0.3.0
 Whoosh==2.6.0
 zope.interface==4.1.2